The prior art sealing rings for the balancing rings of hydraulic motors are bellville washers, as shown in U.S. Pat. No. 3,572,983, constructed from resilient material such as polytetrafluoroethylene. The sealing rings must exclude fluid under pressure of up to 4500 psi from the tongue and groove area of the balancing ring and associated end cap. The axial gap between the balancing ring and the end cap is about 0.081" to 0.095" in the closed assembly in certain motors. The load exerted by the sealing rings on the surface of the balancing ring must be restricted to the inside corners at the tongue, leaving the radial surfaces exposed.
A problem with such prior art polytetrafluoroethylene bellville washers is that they leak because they take a set and lose their preload. A metal bellville washer with sealing material fixed to it would exert an excessive load.
It is an object of the present invention to provide an improved sealing ring for the balancing ring of a hydraulic motor that will provide the desired load without being excessive, that will not take a set and leak, and that will exert load only at such corners of the balancing ring. It is another object of the invention to improve the performance of hydraulic motors by preventing leakage of fluid into the tongue and groove area of the balancing ring and associated end cap, and by preventing the leakage of fluid from the inlet conduit to the outlet conduit.